The present invention generally relates to a surgical device used in a tracheostomy, which is a surgically produced airway introduced directly through the trachea, below the vocal cords.
The vast majority of tracheostomy tubes in current use follow a basic concept consisting of a curved tube which serves as an artificial passage for exchange of air between a patient and an air source, typically either atmospheric air or a mechanical respirator. See, for example U.S. Pat. No. 5,983,895 to Turner. The tube often is enveloped at its caudal end by a small, inflatable balloon, also called a cuff, which is fillable with a fluid, such as air, as it is often necessary to employ positive inspiratory pressure by means of a respirator. See for example, U.S. Pat. No. 5,056,515 to Abel and U.S. Pat. No. 4,791,920 to Fauza. The balloon adheres to the internal lining of the trachea in its cross-section in order to prevent air insufflated by a respirator into a patient from escaping to the environment through the tracheostomy or the larynx and pharynx, which enables the air to reach the lower airways and eventually the pulmonary alveoli. The balloon also aids in supporting the tube inside the trachea.
These conventional tube designs, however, contribute to a variety of frequent complications associated with tracheostomies. Most of these complications are consequences of both the instability of the tube inside the trachea and the pressure inside the balloon.
Instability of the Trachea Tube
Trachea tubes are one of the few, if not only, ballooned tubes currently used in different areas of the human body that are not truly anchored within the body. Consequently, the tube moves a great deal inside the airway, as well as through the tracheal stoma and the wound. This problem is universally observed. Tracheostomy tubes frequently are misplaced inside the trachea, because of this instability and lack of anchorage, leading to a number of different ventilatory problems. Tracheostomy tubes also can be accidentally dislocated, sometimes coming off the airway completely, with possible impaired ventilation, brain damage, or even death in some cases, as reintroduction of the tube can be very difficult.
The continual movement of tracheostomy tubes, for example, due to the rhythm of an artificial ventilator and movements by the patient, is responsible for direct damage to the trachea, mainly at the cranial level of the stoma. One of the most common complications of tracheostomy is stenosis (or stricture) of the trachea at the level of the stoma, which is primarily caused by continual movement of the tube against that area of the trachea, directly damaging the cartilaginous rings. According to studies, a significant proportion of the patients that undergo tracheostomy will have some degree of stenosis of the trachea, usually at the cranial level of the stoma, where the curved portion of the tube produces even more injury as a consequence of its continual movement. This stenosis in turn may produce several long term clinical manifestations, such as intolerance to exercise and recurrent infections, which may require in some patients removal of part of the trachea.
The instability of the tube can also be responsible for other more dramatic complications, for example, damage to the trachea distal (or caudal) to the stoma which results in total perforation of the trachea or structures adjacent the trachea, including the esophagus or the innominate artery. If the innominate artery is perforated, there is a so-called tracheo-innominate artery fistula, with mortality rates around 95%. This kind of fistula may also result from an inflammatory reaction around the stoma that is more intense if there is repeated injury to the area from continual movement of the tube. Those more dramatic, life-threatening complications are rare, but still a possibility nowadays.
Balloon Pressure
High pressures inside the balloon have long been identified as a major cause of damage to the tracheal wall. Such damage may also result in stenosis and/or perforation of the trachea. The concept of a high-volume-low-pressure balloon was introduced in the 1970s, with great impact on the market, exactly because it significantly reduced the pressures inside the balloon and, consequently, the rate and severity of many complications, as compared to previous low-volume-high-pressure balloons. This balloon concept has been used as the xe2x80x9cstandardxe2x80x9d for approximately 30 years. The high-volume-low-pressure balloon, however, is still linked to complications, primarily for two reasons: (1) after a certain degree of expansion, the volume-to-pressure curve of the balloon changes towards that of a low-volume-high-pressure balloon because there is little additional volume inside the balloon, depending on how tight the tube fits inside the trachea; and (2) the continual movement of the tube makes the volume (and thus the pressure) in the balloon very unstable, and also directly forces the balloon against the tracheal wall. Consequently, stenosis and perforation of the trachea still occur at or near the location of the balloon.
It would therefore be desirable to provide a tracheostomy tube and balloon design that is more stable within the patient than currently available tubes, while minimizing pressures within the balloons, thus reducing the occurrence of stenosis and perforations.
Other Design Deficiencies
Infection remains a primary complication of tracheostomy. According to recent reports, approximately 66% of patients with tracheostomies have nosocomial pneumonia and 100% of them have colonization of the airways with bacteria and/or fungi. These complications are primarily due to direct communication between the trachea and the wound through the stoma (and consequently between the trachea and the environment) and aspiration of contents of the pharynx. It would be advantageous to develop a tracheostomy tube and balloon design that is minimizes or prevents infection resulting from these sources.
Another relatively frequent and potentially major complication is obstruction of the tracheostomy tube by mucous plugs. Constant toilette of the tube is mandatory. Another, comparatively minor, complication is the discomfort and/or skin damage caused by straps around the neck that are required to prevent displacement of the tracheostomy tube.
It is therefore an object of this invention to a tracheostomy tube and balloon assembly that is stable within the patient and which minimizes pressures within the balloon in order to avoid or minimize complications associated with the use of standard tracheostomy tube designs.
The present invention relates to a tracheostomy tube with the format and distribution of its balloon designed so as to increased safety of tracheostomies by: enhancing the tube""s anchorability, hence better stabilizing it within the trachea; improving tube placement within the airway; increasing volume, hence lowering the pressure inside the balloon; enhancing the balloon""s volume-to-pressure curve; completely sealing the trachea from the tracheostomy wound, larynx and pharynx; shortening the tube size and providing a movable neck flange.